The present invention generally relates to clutches, and more particularly, it relates to an overrunning clutch for use in an all wheel drive vehicle along with a disconnect device.
In a typical all wheel drive system a front axle is the primary drive, while torque to the rear axle is transferred if and when the average speed of the front wheels spin faster than the average speed of the rear wheels. The torque transfer generally occurs if the front wheels have excessive slip and it also can occur during cornering situations. A clutch works as a mechanical disconnect which prevents torque from being transferred to the rear axle or to the front axle when not desired. Currently known in the prior art are single directional clutches and bidirectional overrunning clutches and clutches that use hydraulic systems to effect changes thereon. The bidirectional overrunning clutch differs from a single directional clutch because it works in both the clockwise and counterclockwise rotation directions. A single directional overrunning clutch is in the overrun mode when the rear axle housing is spinning faster than the front axle housing. This overrun occurs between the two clutch components in the forward vehicle direction when no front wheel slip is present. However, in a single directional overrunning clutch when front wheel slip is encountered during road conditions the axle ratio is overcome in the rear axle and the input side of the clutch drives the output side of the clutch thus delivering torque to the rear wheels until the speed difference between the rear axle and front axle is reduced. Generally speaking the single directional clutch has a torque flow of 50/50 when it uses a bevel gear set. The bevel gear set is engaged when the overrunning single directional clutch is used in combination with an axle ratio offset whenever the primary axle speed is equal to is greater than the secondary axle speed. This usually is the case when front wheel slip occurs for a primary front wheel drive vehicle, and rear wheel slip in a primary rear wheel drive vehicle.
However, problems have occurred with prior art devices that use single directional clutches because the single directional overrunning clutch is oriented only for forward rotation of the axis and an entirely different device is needed for the reverse direction to have a properly operating all wheel drive vehicle. Therefore, whenever a vehicle is put into the reverse direction, the single directional overrunning clutch would never engage and torque would never be transmitted through the rear axle which is the preferred axle to have as the primary drive axle when an all wheel drive vehicle is moving in a reverse direction. Therefore, prior art devices attach an extra housing and/or electronic devices to ensure that the rear axle delivered torque during reverse motion of an all wheel drive vehicle. This may increase costs, weight and reliability of the all wheel drive systems and furthermore increase noise, vibration and harshness issues for the operator of the all wheel drive vehicle.
Therefore, there is a need in the art for a one way overrunning clutch mechanism that works in unison with a disconnect device, such that when the reverse gear is chosen the reverse differential will be able to transmit torque thus providing superior handling and power.
One object of the present invention is to provide a novel all wheel drive axle disconnect device.
Another object of the present invention is to provide a torque transfer device that is capable of disengaging when used in a conventional 50/50 split drive train.
Yet a further object of the present invention is to provide a disconnect device for use in an all wheel drive vehicle that requires minor modification to the existing axle housing.
Still another object of the present invention is to provide an axle disconnect device that has reduced weight and smaller packaging issues for an all wheel drive vehicle.
Yet a further object of the present invention is to provide an axle disconnect device that has torque transfer when operating in a reverse direction.
To achieve the foregoing objects and axle disconnect device for use with an all wheel drive vehicle includes a one-way overrunning clutch. The axle disconnect device also includes a spring contacting the clutch on one end. A spline locking ring is then in contact with the spring on an end opposite to that of the clutch. The axle disconnect device also includes a friction spline that engages a surface of the spline locking ring. The axle disconnect device further includes a differential ramp ring which contacts the friction spline. Finally, the axle disconnect device includes a cover ramp which engages the differential ramp ring such that when the differential ramp ring and the cover ramp interact with one another an axial force is created.
One advantage of the present invention is that the axle disconnect device will be able to be used in a conventional 50/50 all wheel drive vehicle.
A further advantage of the present invention is that the conventional 50/50 split of an all wheel drive vehicle is retained while the torque transfer device is installed in the differential carrier.
A further advantage of the present invention is that the axle disconnect device requires no major modifications to the existing axle housing of the vehicle.
A further advantage of the present invention is that the axle disconnect device will reduce the weight of the drive train.
Yet a further advantage of the present invention is that the axle disconnect device will optimize packaging issues for the drive train of the all wheel drive vehicle.
Still a further advantage of the present invention is that the axle disconnect device will work in harmony with an overrunning clutch to provide all wheel drive in a forward direction and proper torque application when an all wheel drive vehicle is placed in a reverse direction.
Other objects, features, and advantages of the present invention will become apparent from the subsequent description and appended claims taken in conjunction with the accompanying drawings.